Valve operating mechanism



Nov. 24, 1931. J. L. RAY

VALVE OPERATING MECHANISM Filed July 30, 1929 FIG. l.

INVENTOR .3. L-

WITNESS ATTO RN EY i or Patented Nov. 24, 1931 UNITED STATES PATENT OFFICE JAMES L. RAY, OF SWARTHMORE, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELEC- TRIO & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA VALVE OPERATING MECHANISM Application filed July 30, 1929. Serial No. 882,237.

My invention relates to agoverning mechanism for a prime mover, more particularly to'the governing mechanism for a prime mover having a plurality of admission valves of different capacity, and it has for its object to provide a mechanism of the character set forth having improved operation.

It is a more particular object of my invention to provide a governing mechanism which, for any given fluid admission, opens the valveor valves providing such admission with minimum throttling.

In a steam turbine, it is the general practice to divide the nozzles into two or more groups. Considering a two-group arrangement, for example, in which the primary group is larger than the secondary group, the general practice is to make the nozzle ratio for the primary group correct for the pressure drops resulting when the primary is brought into action first, and the ratios for the secondary nozzles correct for the pressure drops when they are brought into action following the primary group. Due to the fact that considerable throttling takes place at light loads with this arrangement, the efficiency is not as high as can be obtained by bringing the secondary nozzles into action ahead of the primary nozzles, so that, although the nozzle ratio is incorrect, the throttling at light loads is much reduced and the efliciency is increased. However, at some higher load, this .arrangement ceases to be as etficient as the original arrangement, that is with the primary group brought into action first, followed by the secondary group.

It is a particular object of my invention, therefore, to provide a means for automatically causing the governor, upon operation 40 in admission-increasing direction, to open the fluid admission means to the secondary group first, closing the same at some predetermined load and simultaneously opening the admission to the primary group, and thereafter also opening the admission to the secondary group. 7

In accordance with my invention, I provide means controlled by the governor for changing the sequence of Zoperation of the valves, Thusfor thesmaller amounts of fiuid admission, the admission valve for the smallest nozzle group is opened, and as the required admission is increased beyond the capacity of such nozzle group, the sequence 1s changed so that a larger nozzle group provides the required admission. The first valve is closed until the required admission becomes great enough for its opening in addition to the other valve or valves.

The above and other objects are effected by my invention as will be apparent from the following description and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. 1 is a diagrammatic view of a governing mechanism in accordance with my invention; and

Fig. 2 is a sectional view, taken along the line II-II of Fig. 1, and showing primary and secondary nozzle groups within an elastic fluid turbine.

Referring now to the drawings more in detail, I show a steam turbine 8 having a primary nozzle group 9 .and a secondary nozzle group 10 for expansion of the steam in the initial stage of the turbine. The primary nozzle group consists of a considerably larger number of nozzles than the secondary group.

Steam or other suitable motive fluid is supplied from any suitable source through a conduit 13, and the admission thereof to the primary and secondary nozzle groups is controlled by suitable valve means such as primary and secondary valves 11 and 12, respectively, communicating with said groups through conduits 14 and 15, respectively, as shown in the drawings.

The turbine is provided with any suitable form of governor, such as a speed-responsive fly ball governor 16, which operates a rock shaft 17 through a connecting rod 18 and a lever 18. The governor moves the lever 18' upwardly to rock the shaft 17 in the direction indicated by the arrow for increased motive fluid admission and in the opposite direction for decreased admission.

The rock shaft 17 has a lever 19 fixed thereon for controlling the primary valve 11. The lever. 19 is connected, through a link 21, to

vso

one end of a lever 22, which is pivoted to a push rod 23 constitutinga movable fulcrum for the lever. At its other end, the lever 22 is pivoted to a sleeve 24 slidable on a link 25.

The link 25 is connected to and controls a fluid pressure relay mechanism 26, which actuatesthe valve 11. The, construction and operation of such a relay is well known and understood in the art and for the present invention it is suficientto state that as the link 25 moves downwardly, the relay moves the valve in opening direction, and vice versa. The link 25 is biased upwardly by aspring 27, and it is provided with a collar 28, against which the sleeve 25 abuts to move the link downwardly upon snflicient movement.

1 The secondary valve 12 is controlled in the same manner by the shaft 17v by similar mechanism, the parts thereof being designated by the same reference numerals witha prime mark affixed. The push rods 23 and 23!, are biased clownwardly by springs 29 and 29 to contact against cams 3-1 and 3]. fixed on a cam shaft 32;As shown on the drawings, the cams are arranged to raise thepush rod 23 and to lower the push rod 23 in; one position of the cam shaft 32, and to reverse these positions in a second position of the cam shaft.

A pinion 33 is fixed on the shaft 32 and meshes with a rack' 34'connected to a piston 35 in a cylinder 36-. The piston 35. is con trolled by a pilot valve 37 disposed in a pilot valve casing 37 and-having piston portions 38 and39 controlling the admission to and exhaust of fluid pressure from ports 41 and 42 communicating with the upper and lower ends of the cylinder 36 The casing 37 is also provided with a fluid admission port 43- and fluid discharge ports 44 and 45. The pilot valve 37 is controlled by the rock shaft 17, to which it isconnected through a lever 46 and a link 47.-

The operation of the above'described apparatus is as follows:

When the governor is positioned in advance of a predetermined, point in thedirection of increasing admission; that is for low load, the piston portions of the pilot valve 37 are disposed belowthe ports 41 and 42, respectively, and" fluid pressure is admitted to the lower end of the cylinder 36 to maintain the piston 35 at the upper end of its stroke. At this position of'theupiston 35', the cam shaft is in the position shown on the drawings, in which the cam 31 maintains the push rod- 23 in: raised position and the cam 31 maintains-the push rod-23 in lowered posi- .The raising of the push rod 23 raises the sleeve 24 so as to'provide lost motion between the sleeve 24 and the collar 28. The sleeve 24 thus slideslon the link 25 during movements ofthe governor without actuating said link, which is held in raised position by the spring 27 to maintain the primary valve 11 closed.

The lowering of the push rod23, however, brings the sleeve 24' into abutment with the collar 28, and movements of the governor are transmitted thereby to effect incremental opening and closing movements ofthe secondaryvalve 12. L

Thus during light loads, steam is admitted to the smaller group of nozzlesandthe throttling thereof is less than if the primary group were used, f I As the governor passes said predetermined point in moving in admission-increasing direction,,however, the piston portions of the pilot valve 37 are brought above the ports 41 and '42, the piston 35 is'brought to lowermost position. The camshaft 32is thus rotated by means of the rack 34 and the pinion 33, in this case 180. In thisposi-tion, the push rod 23 is brought to a lowered position by the cam. 31. This position is; such that the sleeve 24 abuts the collar 28- and movesthe same downwardly initially an amount: sulfiie-nt to effect an opening of the primary valve 11'which will carry approximately the same load carriedby the secondaryvalve 12 before operation ofthe cam shaft 32'.

Alternatively, the cam 31 may bepositioned to effect a slightly less opening, so that the governor must -move somewhat beyond the predetermined point to providethe same fluid admission. The advantage of the latter arrangement is that it"lessens the number of reversals of the cam. shaft' 32, while :the load is fluctuating inthe vicinity corresponding to'said predetermined of the governor.

The cam 31, at the same time,moves the push rod 23 upwardly so as to produce lost motion-between the sleeve 24" and the collar 28. The amount of this lost motion is such that as the load increasesbeyond the capacity of the primary nozzle group,'the lost motion is taken'up and'the governor again effects incremental opening of the secondary valve 12, now in addition to opening ofthe primary valve 11. I 1

The link 47 is provided with suitable means to adjust the length thereof, whereby the point at which the cam shaft 32 operates may be varied. i The valves are operated in reverse order, as willbe-apparent, upon decrease in load and movement ofthe creasing direction. 7 From the above descriptiomit willbeseen that I have provided mechanism for opening a valve incrementally a plurality of times upon movement of the governor in admissionincreasing direction, whereby a valve or a combination of valves involving minimum throttling may be used at each load. 7

While I have shown my invention in but point in the movement ployed, it will be obviousto those'skilled in governor in admissionde a one form in which two nozzle groups are emthe art that it is not so limited but is susceptible of various changes and modifications, without departing from the spirit thereof. For example, the invention may be employed with a larger number of nozzle groups, and more than two positions of the cam shaft may be provided. I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is:

1. The combination with a prime mover having two admission valves, of a governing mechanism therefor comprising means responsive to an operating condition of the prime mover, mechanism controlled by said means for successively operating said valves, and means controlled by the first-mentioned means for changing the order of operation of said valves by said valve-operating mechanism.

2. The combination with a prime mover having two admission valves, of a governing mechanism therefor comprising a governor responsive to the speed of the prime mover, mechanism controlled by the governor for successively operating said valves, and means controlled by the governor for changing the order of operation of said valves by said valve-operating mechanism.

3. The combination with a prime mover having a plurality of admission valves, of a governing mechanism therefor comprising means responsive to an operating condition of the prime mover, means for successively operating said valves including a fulcrumed lever controlling each valve, and means for changing the positions of the fulcrum points of said levers to change the order of operation of said valves by said valve-operating mechanism.

4. The combination with a prime mover having a plurality of admission valves, of

a governing mechanism therefor comprising means responsive to an operating condition of the prime mover, means for successively operating said valves including a fulcrumed lever controlling each valve, and means controlled by the first-mentioned means for simultaneously changing the positions of the fulcrum points of said levers to change the order of operation of said valves by said valve-operating mechanism.

5. The combination with a prime mover having a plurality of admission valves, of a governing mechanism therefor comprising a governor responsive to the speed of the prime mover, mechanism for successively operating said valves including a fulcrumed lever controlling each valve, a cam shaft having a cam thereon for changing the position of the fulcrum point of each lever, said cams and levers being arranged so that in one position of the cam shaft the valves are operated in one sequence and in another po sition thereof they are operated in another sequence, and means for operating said cam shaft to one of said positions when the governor is positioned to provide less than a predetermined admission and to the other position when the governor is positioned for more than the predetermined admission.

6. The combination with a prime mover having two admission valves of different capacity, of a governing mechanism therefor comprising a speed-responsive governor, connecting means including a lost motion connection between the governor and each of said valves, whereby tne governor controls each. valve incrementally, and means controlled by the governor for controlling the lost motions whereby the governor effects successively. upon operation in admission-increasing direction, first opening of the smaller valve, then opening of the larger valve and closing of the smaller valve and thereafter opening of the smaller valve.

7. The combination with a prime mover having two admission valves, of a governing mechanism therefor comprising a speed-responsive governor, connecting means between the governor and the valves whereby the governor controls said valves incrementally and including a lost motion connection between the governor and one valve, and means controlled by the governor for varying the time of operation of said valve with respect to operation of the governor by taking up said lost motion.

8. The combination with a prime mover having a plurality of admission valves, of a governing mechanism therefor comprising a governor responsive to an operating condition of the prime mover, means for operating said valves in timed relation with respect to operation of the governor, and means controlled by the governor for simultaneously changing said timed relation of a plurality of valves so as to move one valve in closing direction and another valve in opening direction.

9. The combination of a prime mover having a small and a relatively large admission valve, and means for first opening the small valve incrementally, then closing the small valve and opening the large valve to substantially the same opening, increasing the opening of the large valve and thereafter again opening the small valve in addition to the large valve.

' 10. The combination of a prime mover having two admission valves one of which is of greater capacity than the other, and means for operating said valves in response to an operating condition of the prime mover, said means, upon operation in valve opening direction, opening first the small valve incrementally, then closing the small valve and simultaneously opening the large valve to provide substantially the same admission,

then increasing the opening of the large valve to fully open position, and thereafter opening the small valve in addition to the large valve.

- 11-. The combination with a prime mover having a relatively small and a relatively large admission valve, of a governing mechanism. therefor comprising a governor responsive to an operating condition of the V prime mover, means for operating said valves in timed relation With respect cooperation of the governor and first moving the small valve in opening direction upon beginning of movement of the governor in valve opening direction, and means effective upon operation of the governor past a predetermined point in valve opening direction for simultaneously changing the timed relation of said valves with the governor so as to effect closing of the small valve and opening of the large valve to provide substantially the amountof admission provided by the small valve before being closed.

1 12. The combination of a prime mover having a small and a relatively large admission valve, and means for first opening the small valve incrementally, then closing the small valve and opening the large valve to substantially the same opening, and then increasing the opening of the large valve.

13. The combinationof a prime mover having two admission valves one of which is of greater capacity than the other, and means for operating said valves in response to an operating condition of the prime mover, said means, upon operation in valve opening direst-ion, opening first the small valve incrementally, then closing the small valve and simultaneously opening the large valve to 46 provide substantially the same admis i and then increasing the opening of'the large valve.

14. The combination with a prime mover having a relatively small and a relatively large admission valve, of a governing mechanism therefor comprising a governor responsive to an operating condition of the prime mover, connecting means between the governor and each valve whereby the governor controls the valve increment-ally, and means controlled by the governor and acting on the connecting means of the small valve to efi'ect closing of said valve as the governor moves past a given point in valve-opening direction and to maintain said valve closed for a certain travel'of the governor beyond said point and acting on the connecting means of the large valve to maintain said'valve closed as the governor begins travel in valve opening direction and permitting said valve to open as the governor passes said point.

In testimony whereof, I have hereunto subscribed my name this 25th day of July, 1929.

JAMES L. RAY. 

